#define _CRT_SECURE_NO_WARNINGS 1
#include"Date.h"

// 获取某年某月的天数
int Date::GetMonthDay(int year, int month)
{
	static int days[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
	int day = days[month];

	if (month == 2 && ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)))
	{
		day += 1;
	}

	return day;
}

// 全缺省的构造函数
Date::Date(int year, int month, int day)
{
	//对非法日期的检测
	if (year < 1900 || month < 1 || month > 12 || day < 1 || day > GetMonthDay(year, month))
	{
		cout << "非法日期" << endl;
	}

	_year = year;
	_month = month;
	_day = day;
}






void Date::Print()
{
	cout << _year << "-" << _month << "-" << _day << endl;
}



// 日期+=天数
// d1 += 10
// d1 += -10
Date& Date::operator+=(int day)
{
	if (day < 0)
	{
		return *this -= -day;
	}

	_day += day;

	while (_day > GetMonthDay(_year, _month))
	{
		_day -= GetMonthDay(_year, _month);
		_month++;

		if (_month == 13)
		{
			_year++;
			_month = 1;
		}
	}
	return *this;
}



// 日期+天数
// d + 10
Date Date::operator+(int day)
{
	Date ret(*this);
	ret += day;
	return ret;
}



// 日期-天数
Date Date::operator-(int day)
{
	Date ret(*this);
	ret -= day;

	return ret;
}



// 日期-=天数
// d -= 100
// d -= -100
Date& Date::operator-=(int day)
{
	if (day < 0)
	{
		return *this += -day;
	}

	_day -= day;

	while (_day <= 0)
	{
		--_month;

		if (_month == 0)
		{
			--_year;
			_month = 12;
		}

		_day += GetMonthDay(_year, _month);
	}

	return *this;
}



// 前置++
// ++d -> d.operator++(&d)

Date& Date::operator++()
{
	*this += 1;
	return *this;
}



// 后置++
// d++ -> d.operator++(&d, 0)

Date Date::operator++(int)
{
	Date ret(*this);
	*this += 1;
	return ret;
}



// 后置--
Date Date::operator--(int)
{
	Date ret(*this);
	*this -= 1;

	return ret;
}



// 前置--
Date& Date::operator--()
{
	*this -= 1;

	return *this;
}



// d1 > d2
// >运算符重载
bool Date::operator>(const Date& d)
{
	if (_year > d._year)
	{
		return true;
	}

	else if (_year == d._year)
	{
		if (_month > d._month)
		{
			return true;
		}

		else if (_month == d._month)
		{
			if (_day > d._day)
			{
				return true;
			}
		}
	}
	return false;

}



// ==运算符重载
bool Date::operator==(const Date& d)
{
	return _year == d._year

		&& _month == d._month

		&& _day == d._day;
}



// 下面复用上面两个的实现
// >=运算符重载
bool Date::operator >= (const Date& d)
{
	return *this > d || *this == d;
}



// <运算符重载
bool Date::operator < (const Date& d)
{
	return !(*this >= d);
}



// <=运算符重载
bool Date::operator <= (const Date& d)
{
	return !(*this > d);
}



// !=运算符重载
bool Date::operator != (const Date& d)
{
	return !(*this == d);
}



// d1 - d2
// 日期-日期 返回天数
int Date::operator-(const Date& d)
{
	int flag = 1;
	Date max = *this;
	Date min = d;

	if (*this < d)
	{
		max = d;
		min = *this;
		flag = -1;
	}

	int day = 0;
	while (min < max)
	{
		++(min);
		++day;
	}

	return day * flag;
}